Black tea consumption improves postprandial glycemic control in normal and pre-diabetic subjects: a randomized, double-blind, placebo-controlled crossover study.

BACKGROUND AND OBJECTIVES Postprandial glycemic control is important for prevention of diabetes. Black tea consumption may improve postprandial glycemic control. The major bioactive compounds are polyphenols, black tea polymerized polyphenol (BTPP).This study examined the effect of black tea consumption on postprandial blood glucose and insulin response following sucrose loading in normal and pre-diabetes subjects. METHODS AND STUDY DESIGN This study was a randomized, double-blind, placebo-controlled crossover study. Twenty-four subjects, male and female aged 20-60 years, normal and pre-diabetic, randomly ingested a sucrose solution with a low dose (110 mg BTPP), a high dose (220 mg BTPP) of black tea drink or a placebo drink (0 mg BTPP). Blood samples were collected at 0, 30, 60, 90, and 120 min from commencement of drink ingestion to measure blood glucose and insulin levels. RESULTS The drink containing low dose and high dose BTPP significantly decreased incremental blood glucose area under the curve (AUC) after sucrose intake compared with placebo in the normal (T0-60 min 3,232±356 vs 3,295±312 vs 3,652±454 mg.min/dL; p=0.016) and pre-diabetic subjects (T0-60 min 2,554±395 vs 2,472±280 vs 2,888±502 mg.min/dL; p=0.048). There was no statistically significant difference of changes in insulin levels between the placebo and black tea groups (p>0.05). No significant differences in adverse effects were observed with the placebo, low dose and high dose of BTPP groups. CONCLUSION Black tea consumption can decrease postprandial blood glucose after sucrose intake.